Electric-current transformer.



No. 628,807.. Patented July ll, I899. sa.. K. HUMPHREY. ELECTRIC; CiURRENT TRANSFORMER.

[Application filed Oct. 1, 1898.]

4 Sheets-Sheet I.

WITNESSES A TTOHNE YS.

No. 628,807. I Patented July H, I899.

S. K. HUMPHREY.

ELECTRIC CURRENT TRANSFORMER.

(Applicatiol. filed Oct. 1, 1898.)

4 Shoots-Shut 2,

no Model.)

WITNESSES 1w: NORMS PETERS 00., Pncnau'rmz, WASHINGYON. o. c

No. 628,807. -Patented luly ll, I899. S. K. HUMPHREY.

ELECTRIC CURRENT TRANSFORMER.

(Application filed Oct. 1, 189B.)

4 Sheets-8heet 3.

(N0 HMIGE.

/N VENTOH MIA/5385s m: NORRIS versus 03., mom-umu, WASNINGYON, a c,

No. 628,807. Patented luly II, I899,

S. K. HUMPHREY.

ELECTRIC CURRENT TRANSFORMER.

(Application filed Oct. L 1898) 4 Sheets-Sheet 4.

(No Modal.)

WITNESSES.

UNITED STATES "PATENT OFFICE.

SETH KING HUMPHREY, OF BOSTON, MASSACHUSETTS.

ELECTRIC-CURRENT TRANSFORMER.

SPECIFICATION forming part of Letters Patent No. 628,807, dated July 1 1, 1899. Application filed October 1, 1898. Serial No. 692,408. (No model.)

To all whom it may concern.-

Be it known that I, SETH KING HUMPHREY, of Boston, in the county of Suffolk and State of M assachusetts, have invented a newand Improved Electric-Current Transformer, of which the following is a full, clear, and exact description.

This invention relates to an improved de vice designed to transform multiphase electric currents from one voltage to anotherand at the same time from alternating to a single direct current without the employment of rotary transformers.

I will describe an electric-current transformer embodying my invention and then point out the novel features in the appended claim.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which- Figure l is a diagrammatic view of a transformer embodying my invention, and Figs. 2, 3, and 4 are diagrammatic views, respectively, of the secondary, primary, and auXi-liary windings.

For convenience I describe a transformer designed to be connected to a three-phase alternating-current circuit. It consists of a core A, built up. of many thicknesses of softiron disks, which are electrically insulated from each other. This core is solid, excepting that a series of holes is provided (here shown as twenty-four) through which the windings are threaded. This subdivision of windings would in practice be materially increased and the construction altered to facilitate winding. The heavy lines B represent the secondary circuits, and the light lines 0 represent the primary circuits. The several windings are through the openings at to at, inclusive, and over the periphery of the core. The primary windings have one connection with each of the mains D, E, and F from the generator. Each main is connected in series with a plurality of sections (here shown as six, in groups of two) diametrically opposite each other, and thence the ends are connected together. This gives the well-known rotatin g magnetic field. Any other connection of the several sections with the mains of any multiphase system that will give a rotating magnetic field can be used.

The secondaryisacontinuouswindingsimil'arto that of a Gram me ring distributed either over, under, or by the side of the several sections of the primary windings, so that both primary and secondary windings have at every coil a common magnetic circuit. The secondary is tapped between each coil at the points numbered,consecutively, from 1 to 24-, and the parts so numbered arc to be connected with like-numbered segments on the stationary commutator G. I have shown, however, but two of the coils having such connection. In the particular instance shown in the drawings it will be considered that the current in the main D is at its maximum positive flow and the mains E F are equally negative. This creates a positive pole at N and a negative pole at S, and the magnetic flux is from the neighborhood of N between the coils extended through the openings cfg h, &c., and across the center of the transformer to enter between the coils through the openings 1 r 315, (be. The rotation of the flux being shown as left-handed, this induces a current in the secondaryat both Nand S upward from the coil 13 to the coil 1 on both sides of the transform er, the action being very similar to that in the armature of a directcurrent dynamo. The magnetic flux is from N to S, and as the coils 1 and 13 of the secondary are cutting practically no lines of force at this instant these are the neutral points of greatest difference of potential. As the field rotates, the points having the greatest difference of potential travel successively from 1 to 2 3, &c., and from 18 to 14 15, &c., and being connected to the stationary commutator G create on the commutator a lefthanded rotating potential.

I have shown the commutator as having twice as many segments as there are coils in the transformer. They are cross-connected, .as at m, so that the rotating potential in the commutator rotates one-half as fast as the rotating magnetic field in the transformer. This ratio of commutator-segments to transformercoils can be altered to suit circumstances; but for the purpose of gathering the current by rotating brushes against the commutator it is generally necessary to reduce the speed of rotation of potential. In the particular instance shown the points of greatest difierence of potential being 1 and 13 in the transformer lhoro are two pairs of brushes )2 11 and o o, covering corresponding segments of the commutator, said brushes being cross-connected, as at p q, and each pair is designed to be connected to a collecting-ring en the shaft of the tionary brushes will take the direct current. The motor used (not shown) to carry these brushes would be a synchronous four-pole motor run from the same three-phase mains. The comm utator-dial should have an adjusting motion through a small are to get the brushes to coincide with the points of greatest difference of potential while running. The coils momentarily short-zircnited by the brushes are at their neutral points, and reactions in these coils, as well as in other parts of the trans former, as I have heretofore stated, will be Very similar to those in a direct-current dynamo.

exerts a powerful directional influence on the rotating field. motor driving them, from which rings sta- One of the distinctive features of this deiron magnetic circuit of its own.

The coils].

j 2 2t and 12, 13, and 1:1: are cutting Very few So far I have described only the transformer lines of force, and as the dilterence of potential between 1. and 13 is created by the intensity of the magnetic flux across the center from N to S without regard to whether said lines of force flow between the coils l) and 0, 7' and lb, or between any intermediate coils, this difference of potential is proportional to the total number of lines of force and can vary only as the intensity of magnetization varies. It has been conclusively shown that the intensity of magnetization in a rotating field created by a well-balanccd multiphase system is practically constant.

instant shown tends to create a magnetic flux 3 from N to S; but the secondary current from 13 to 1 on both sides of the transformertends to send magnetic fluxfrom between the coils extended through (1, and 0; across the center to enter between the coils extended through Zand m thus tending to create a magnetic field at right angles to the transformer field. The primary coils would of course take additional current to overcome the distorting effect of this secondary field; but in order to assist the primary winding in maintaining a rotating magnetic field of uniform speed and intensity I place an auxiliary rotating fieldwinding H from each of the three generatormains across the center of the transformer,

as shown, similar to and in parallel with the periphery-win dings. These windings are opposite to the primary transformer-windings, and thus create a rotating magnetic flux, which at the instant shown is from X to S and always coincides with the magnetic flux Therefore the rotating potential is constant and when gathered at the comm utator-rings on the synchronous motor will give a con- 1 stant-potential direct current subject only to the drop caused by an increased demand on the circuit for current.

Having thus described my invention, I claim as new and desire to soon re by Letters 1 Patent A transformer, comprising a core consisting of a disk having a series of openings through it, a multiplicity of primaries rove through said openings and over the periphery of the 1 disk, the said primaries being arranged in a f plurality of sets placed opposite each other and connected, one set, with the opposite set, a continuous secondary winding consisting of a series of coils, each having connection with segments of a stationary commutator, I and auxiliary windings extended across the center of the disk and connected in parallel i with the primaries, substantially as specified.

due to the primary windings on the periphery.

As this auxiliary winding is not interlinked in any way with the secondary, it will have SETH KING IIUMPIIREY. \Vitnesses:

EFFIE Loan, E. G. ODYON. 

